This invention relates to continuous oxygen enrichment systems, and relates more particularly to method and apparatus for recovering waste energy therefrom.
Continuous oxygen enrichment or oxygen separation systems are operable to continuously separate an airflow into oxygen-depleted and oxygen-enriched gas streams through use of a membrane which has relatively high permeability characteristics with respect to oxygen and relatively low permeability to nitrogen. Examples of such separation devices may be found in U.S. Pat. No. 4,198,213 to Scott A. Manatt, as well as copending U.S. Patent Application Ser. No. 289,861 filed Aug. 4, 1981, now U.S. Pat. No. 4,508,548, entitled "Air Oxygen and Nitrogen Concentration Device" and having common assignee with the present application. As discussed in greater detail in the above-referenced patent and application there are various manners of utilizing the resultant oxygen-enriched and oxygen depleted gas streams. For example, oxygen-enriched gas streams are quite useful in aircraft for increasing the oxygen content of air for breathing, particularly at higher altitude levels. Also, the oxygen-depleted, or in other words a nitrogen enriched gas stream has utility for inerting fuel tanks or other enclosed spaces. Characteristically, such systems are capable of continuously supplying the oxygen-enriched and oxygen-depleted air streams in contrast to other prior art arrangements wherein oxygen concentrated gases are generated on intermittent or batch stream bases. To operate on a continuous basis, a relatively high pressure differential must normally be maintained across the oxygen permeable membrane.